[1] Department of Neuro-ophthalmology,
[2] National Hospital for Neurology and Neurosurgery,undefined
[3] University College London Hospitals NHS Trust,undefined
[4] London WC1 N 3BG,undefined
[5] UK e-mail nophth@sonnet.gpo.co.uk Tel.: +44-171-8373611 ext 3388 Fax: +44-171-2090751,undefined